Parts



a State of UNITED STATES PATEN OFFICE.

JAMES F. sALLows, or LANSING, MICHIGAN, ASSIGNOR 'ro THE sALLows PATENTED STEEL TREATING PROCESS COMPANY, or" LANSING, MICHIGAN.

PROCESS FOR PRODUCING Afi 'D FINISHIHG GEARS AND OTHER CARBONIZED-STEEI I PARTS. 1

To all whom it may concern."

Be it known that I, JAMES F. SALLOWS, a citizen of the United States, and a resident of the'citfiof Lansing,

ichigan, have invented certain new and useful Improvements in Processes for Producing and Finishing Gears and.

other carbonized-Steel Parts, of which the following isa specification.

The purpose of this invention is to pro vide an improved process for producing carbonized and hardened steel parts requiring accuracy of dimension and form without rinding as the final process of finishing to orm and treating for removing scale, because the usual steps of carbonizing and hardenin roduce not only internal stresses but also eformation, and tool finishing can not be resorted to after the hardening is completed, and therefore the deformation can be corrected only by a process which can be applied to the hardened material such as, for example, the process of grind ing and polishing;

have overcome this difficulty bythe following process:

I first produce as by forging the article desired in the rough, or of approximately the form and dimension required. I next rough-machine the part to a still closer approximation of the form and; dimension required but to a substantially uniform oversize. For the third step I case-harden the part employing the usual means and processes for carbonizing it quite deeply, upon the conclusion of the carbonizing step I quench the parts directly in oil, first allowing them to cool in the pots to the proper temperature for hardenlng and refimng the core by quenching The case produced should exceed'the oversize by the depth of the case desired in the finished part.

As the next step, I box the parts in car- "bon dust, that is, inclose them in a box and pack with carbon dust, and heat the package to proper temperature for annealing, that is to say, about 1400 degrees F., and permit it to remain in the heating furnace a proper length of time to produce the decounty of Ingham,

Specification of Reissued Letters Patent. Reissued Mar, 16, 1920.

No Drawing. Original No. 1,232,462, dated October 22, i918, Serial No. 205,976,

Application for reissue filed December 15, 1919. Serial No. 345,032.

med December 7,

, sired structure of the case. then removethe package from the furnace and allow it size of the part, so that substantially no lace in either the expanchanges will take sion of shrinkage forces already in the part. The parts are then ing material and quenched in either Oil or wager, depending upon the kind of steel use The parts produced in this manner are found to have the form and dimensions to which they were finish-machined, without Warping or distortion of anysort, and apparently without injurious internal stresses. Having thus described my invention, what I claim as new and desire to'secure by Letters Patent is:

1. The process of and hardened steel following steps: first, rough forming the parts; second, rough-machining parts to approximately the form and outline required; third, carbonizing deeply and quenching in producing carbonized oil; fourth, annealing by boxing in mod-' parts comprising the sixth, reboxing in removed from the 'packeparts; Y

oversize by the depth of the case desired in my hand 'and' seal in the presence of two the finished part by case hardening process witnesses. and quenching; fburth, annealing by heating and eoblin While unex osed to the at-. v 5 mosphere; fift 1, machine ishing; sixth, Witnesses:

reheating slowly and quenchin D. J, MEAD,

In witness whereof I have ereuntq set' F. S.- PORTER.

JAMES F. SALLOWS. 

